I assume abuse mostly refer to spam / unconscious use of the network functionalities and is related to its cheapness: What is cheap is abundant and we're quick to waste resources right?
I think bigger data fields are out of question due to Stellar ambitions: not every project do it the same way but basically we don't know how to combine together low fees, high transaction output, wide adoption and large storage capabilities. Some technologies like sharding may end up giving us a solution but we're not here yet.
But clearly Stellar needs an on-chain messaging system so at least people can use their custom network as a decentralized database. On main-net you'd pay one basefee/64b to pack data so it's unlikely to generate as much abuse than other functionalities such as trade or payment which are cheaper. But if people are willing to pay for it then why not let them do so? I mean, how is it less legit than eating space for trading offers, payment, asset issuance and so on?